The role of self‐Ia antigens in the murine mixed lymphocyte response

Abstract

Mouse splenic macrophages (MΦ) were tested for their ability to potentiate in vitro allogeneic mixed lymphocyte response (MLR) of highly purified syngeneic responder T cells against allogeneic MΦ. It was shown that even extremely low numbers of MΦ, syngeneic to the responder T cells were able to induce significantly stronger MLR. This potentiating effect was demonstrated to be expressed via the self-Ia antigens present on the surface of syngeneic MΦ., The functional involvement of self-Ia antigens was substantiated by two approaches: (a) by using monoclonal antibodies specific for I-region determinants of the responder haplotype MΦ, and (b) by setting up MLR cultures with stimulator MΦ of (responder X stimulator) F₁ origin which express both self- and allo-Ia antigens. The results obtained in this study demonstrate that the presentation of self-Ia antigens, in conjunction with the recognition of allomajor histocompatibility complex antigens, are required for in vitro primary MLR.